UNIVALVE SHELLS. 49 



contiguous to the walls of the shell; outside of a pale cream 

 colour, perlaceous within. 



Inhabits the American and Indian oceans. 



V Siphunculus, ww w w w chambers. 



The curious structure of the shell of the Nautilus Pompilius, (which 

 also runs, -with some variation, through the whole genus,) cannot be 

 contemplated \\-ithout admiration, each cell or camera communicating 

 with the next by a small and short tube, the first or principal cell being 

 far larger than the rest, and appearing destined to contain the chief 

 part or body of the inhabiting animal, the nature of which is not yet 

 properly understood. It appears, however, to be in some degree allied 

 to the genus Sepia, but is destitute of long arms or claspers, instead of 

 which it is furnished with several rows of short, broad, subdivided or 

 palmated tentacula, spreading in a radiated direction round the mouth 

 or beak : it is also provided ^dth a concave expansile hood or process, 

 which it is supposed occasionally to extend by way of a. sail. 



The animal is figvu-ed in Shaw's Nat. Misc. Plates 579 and 580. But 

 it has been more correctly described and figured by Professor Owen 

 and other anatomists of the present day. 



With a very few exceptions the Nautili have only been found to in- 

 habit the ocean. 



Genus 20.— CONUS. 



Animal a Limax; shell univalve, convolute, turbinate; 

 aperture effuse, longitudinal, linear, without teeth, entire 

 at the base; pillar smooth. 



This genus in the Linnaean System is divided into five families : 

 *having the spire or tiu-ban nearly truncate or flat ; **pyriform, with 

 the base rotundate, and sub-cylindrical, the cylinder one half longer 

 than the spire ; ***elongate, mth the base rotundate, cylinder t^vice 

 the length of the spire ; ****ventricose in the middle, and narrow at 

 each end; *****ventricose, and emits a tinkling sound when thrown 

 on its back upon a table. 



Conus striatus The Striated Cone. Plate VIII. 



fig. 20. Ovate, oblong, gibbous, clouded, and with strong 

 transverse striae. Four inches long. Inhabits Africa and 

 India. 



Conus varius. Plate II. fig. 12. Rubbed through to 

 show the internal structure of the shell, d Spire, f body, 

 M M M pillar or columella. 



The Cones inhabit the ocean, and are generally found on rocky 

 shores. 



